This species is widespread in coastal areas from southern British Columbia to southeastern Alaska. The Washington State Heritage Program tracks this species as "state-rare" in Snohomish County, Washington; I have not seen any specimens to confirm its presence in the state.

Coptis aspleniifolia , C . laciniata , and C . occidentalis form a group of morphologically similar, allopatric species that are probably recently derived. The species may have originated in response to the opening of the western Cordilleran landscape after Pleistocene glaciation and could be considered localized variants of a single species. Although most individuals can be readily distinguished, some can be difficult to place.

A putative hybrid between Coptis aspleniifolia and C . trifolia has been found along the Kennedy River of Vancouver Island, British Columbia (T.C. Brayshaw, pers. comm.). It has 3-5 deeply dissected leaflets per leaf and no complete flowers.